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1120 regels
34 KiB
1120 regels
34 KiB
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#include "db/version_set.h"
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#include <algorithm>
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#include <stdio.h>
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#include "db/filename.h"
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#include "db/log_reader.h"
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#include "db/log_writer.h"
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#include "db/memtable.h"
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#include "db/table_cache.h"
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#include "leveldb/env.h"
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#include "leveldb/table_builder.h"
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#include "table/merger.h"
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#include "table/two_level_iterator.h"
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#include "util/coding.h"
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#include "util/logging.h"
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namespace leveldb {
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static const int kTargetFileSize = 2 * 1048576;
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// Maximum bytes of overlaps in grandparent (i.e., level+2) before we
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// stop building a single file in a level->level+1 compaction.
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static const int64_t kMaxGrandParentOverlapBytes = 10 * kTargetFileSize;
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static double MaxBytesForLevel(int level) {
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// Note: the result for level zero is not really used since we set
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// the level-0 compaction threshold based on number of files.
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double result = 10 * 1048576.0; // Result for both level-0 and level-1
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while (level > 1) {
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result *= 10;
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level--;
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}
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return result;
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}
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static uint64_t MaxFileSizeForLevel(int level) {
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return kTargetFileSize; // We could vary per level to reduce number of files?
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}
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namespace {
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std::string IntSetToString(const std::set<uint64_t>& s) {
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std::string result = "{";
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for (std::set<uint64_t>::const_iterator it = s.begin();
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it != s.end();
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++it) {
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result += (result.size() > 1) ? "," : "";
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result += NumberToString(*it);
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}
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result += "}";
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return result;
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}
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}
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Version::~Version() {
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assert(refs_ == 0);
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for (int level = 0; level < config::kNumLevels; level++) {
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for (int i = 0; i < files_[level].size(); i++) {
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FileMetaData* f = files_[level][i];
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assert(f->refs >= 0);
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f->refs--;
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if (f->refs <= 0) {
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delete f;
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}
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}
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}
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delete cleanup_mem_;
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}
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// An internal iterator. For a given version/level pair, yields
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// information about the files in the level. For a given entry, key()
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// is the largest key that occurs in the file, and value() is an
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// 16-byte value containing the file number and file size, both
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// encoded using EncodeFixed64.
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class Version::LevelFileNumIterator : public Iterator {
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public:
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LevelFileNumIterator(const Version* version,
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const std::vector<FileMetaData*>* flist)
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: icmp_(version->vset_->icmp_.user_comparator()),
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flist_(flist),
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index_(flist->size()) { // Marks as invalid
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}
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virtual bool Valid() const {
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return index_ < flist_->size();
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}
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virtual void Seek(const Slice& target) {
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uint32_t left = 0;
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uint32_t right = flist_->size() - 1;
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while (left < right) {
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uint32_t mid = (left + right) / 2;
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int cmp = icmp_.Compare((*flist_)[mid]->largest.Encode(), target);
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if (cmp < 0) {
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// Key at "mid.largest" is < than "target". Therefore all
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// files at or before "mid" are uninteresting.
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left = mid + 1;
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} else {
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// Key at "mid.largest" is >= "target". Therefore all files
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// after "mid" are uninteresting.
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right = mid;
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}
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}
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index_ = left;
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}
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virtual void SeekToFirst() { index_ = 0; }
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virtual void SeekToLast() {
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index_ = flist_->empty() ? 0 : flist_->size() - 1;
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}
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virtual void Next() {
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assert(Valid());
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index_++;
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}
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virtual void Prev() {
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assert(Valid());
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if (index_ == 0) {
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index_ = flist_->size(); // Marks as invalid
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} else {
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index_--;
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}
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}
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Slice key() const {
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assert(Valid());
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return (*flist_)[index_]->largest.Encode();
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}
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Slice value() const {
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assert(Valid());
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EncodeFixed64(value_buf_, (*flist_)[index_]->number);
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EncodeFixed64(value_buf_+8, (*flist_)[index_]->file_size);
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return Slice(value_buf_, sizeof(value_buf_));
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}
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virtual Status status() const { return Status::OK(); }
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private:
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const InternalKeyComparator icmp_;
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const std::vector<FileMetaData*>* const flist_;
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int index_;
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// Backing store for value(). Holds the file number and size.
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mutable char value_buf_[16];
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};
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static Iterator* GetFileIterator(void* arg,
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const ReadOptions& options,
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const Slice& file_value) {
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TableCache* cache = reinterpret_cast<TableCache*>(arg);
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if (file_value.size() != 16) {
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return NewErrorIterator(
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Status::Corruption("FileReader invoked with unexpected value"));
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} else {
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return cache->NewIterator(options,
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DecodeFixed64(file_value.data()),
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DecodeFixed64(file_value.data() + 8));
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}
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}
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Iterator* Version::NewConcatenatingIterator(const ReadOptions& options,
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int level) const {
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return NewTwoLevelIterator(
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new LevelFileNumIterator(this, &files_[level]),
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&GetFileIterator, vset_->table_cache_, options);
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}
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void Version::AddIterators(const ReadOptions& options,
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std::vector<Iterator*>* iters) {
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// Merge all level zero files together since they may overlap
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for (int i = 0; i < files_[0].size(); i++) {
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iters->push_back(
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vset_->table_cache_->NewIterator(
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options, files_[0][i]->number, files_[0][i]->file_size));
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}
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// For levels > 0, we can use a concatenating iterator that sequentially
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// walks through the non-overlapping files in the level, opening them
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// lazily.
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for (int level = 1; level < config::kNumLevels; level++) {
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if (!files_[level].empty()) {
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iters->push_back(NewConcatenatingIterator(options, level));
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}
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}
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}
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void Version::Ref() {
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++refs_;
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}
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void Version::Unref() {
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assert(refs_ >= 1);
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--refs_;
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if (refs_ == 0) {
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vset_->MaybeDeleteOldVersions();
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// TODO: try to delete obsolete files
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}
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}
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std::string Version::DebugString() const {
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std::string r;
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for (int level = 0; level < config::kNumLevels; level++) {
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// E.g., level 1: 17:123['a' .. 'd'] 20:43['e' .. 'g']
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r.append("level ");
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AppendNumberTo(&r, level);
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r.push_back(':');
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const std::vector<FileMetaData*>& files = files_[level];
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for (int i = 0; i < files.size(); i++) {
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r.push_back(' ');
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AppendNumberTo(&r, files[i]->number);
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r.push_back(':');
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AppendNumberTo(&r, files[i]->file_size);
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r.append("['");
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AppendEscapedStringTo(&r, files[i]->smallest.Encode());
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r.append("' .. '");
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AppendEscapedStringTo(&r, files[i]->largest.Encode());
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r.append("']");
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}
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r.push_back('\n');
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}
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return r;
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}
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// A helper class so we can efficiently apply a whole sequence
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// of edits to a particular state without creating intermediate
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// Versions that contain full copies of the intermediate state.
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class VersionSet::Builder {
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private:
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typedef std::map<uint64_t, FileMetaData*> FileMap;
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VersionSet* vset_;
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FileMap files_[config::kNumLevels];
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public:
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// Initialize a builder with the files from *base and other info from *vset
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Builder(VersionSet* vset, Version* base)
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: vset_(vset) {
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for (int level = 0; level < config::kNumLevels; level++) {
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const std::vector<FileMetaData*>& files = base->files_[level];
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for (int i = 0; i < files.size(); i++) {
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FileMetaData* f = files[i];
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f->refs++;
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files_[level].insert(std::make_pair(f->number, f));
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}
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}
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}
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~Builder() {
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for (int level = 0; level < config::kNumLevels; level++) {
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const FileMap& fmap = files_[level];
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for (FileMap::const_iterator iter = fmap.begin();
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iter != fmap.end();
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++iter) {
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FileMetaData* f = iter->second;
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f->refs--;
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if (f->refs <= 0) {
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delete f;
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}
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}
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}
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}
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// Apply all of the edits in *edit to the current state.
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void Apply(VersionEdit* edit) {
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// Update compaction pointers
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for (int i = 0; i < edit->compact_pointers_.size(); i++) {
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const int level = edit->compact_pointers_[i].first;
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vset_->compact_pointer_[level] =
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edit->compact_pointers_[i].second.Encode().ToString();
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}
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// Delete files
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const VersionEdit::DeletedFileSet& del = edit->deleted_files_;
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for (VersionEdit::DeletedFileSet::const_iterator iter = del.begin();
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iter != del.end();
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++iter) {
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const int level = iter->first;
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const uint64_t number = iter->second;
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FileMap::iterator fiter = files_[level].find(number);
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assert(fiter != files_[level].end()); // Sanity check for debug mode
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if (fiter != files_[level].end()) {
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FileMetaData* f = fiter->second;
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f->refs--;
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if (f->refs <= 0) {
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delete f;
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}
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files_[level].erase(fiter);
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}
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}
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// Add new files
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for (int i = 0; i < edit->new_files_.size(); i++) {
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const int level = edit->new_files_[i].first;
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FileMetaData* f = new FileMetaData(edit->new_files_[i].second);
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f->refs = 1;
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assert(files_[level].count(f->number) == 0);
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files_[level].insert(std::make_pair(f->number, f));
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}
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// Add large value refs
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for (int i = 0; i < edit->large_refs_added_.size(); i++) {
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const VersionEdit::Large& l = edit->large_refs_added_[i];
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vset_->RegisterLargeValueRef(l.large_ref, l.fnum, l.internal_key);
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}
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}
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// Save the current state in *v.
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void SaveTo(Version* v) {
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for (int level = 0; level < config::kNumLevels; level++) {
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const FileMap& fmap = files_[level];
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for (FileMap::const_iterator iter = fmap.begin();
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iter != fmap.end();
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++iter) {
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FileMetaData* f = iter->second;
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f->refs++;
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v->files_[level].push_back(f);
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}
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}
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}
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};
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VersionSet::VersionSet(const std::string& dbname,
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const Options* options,
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TableCache* table_cache,
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const InternalKeyComparator* cmp)
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: env_(options->env),
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dbname_(dbname),
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options_(options),
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table_cache_(table_cache),
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icmp_(*cmp),
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next_file_number_(2),
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manifest_file_number_(0), // Filled by Recover()
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last_sequence_(0),
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log_number_(0),
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prev_log_number_(0),
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descriptor_file_(NULL),
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descriptor_log_(NULL),
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current_(new Version(this)),
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oldest_(current_) {
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}
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VersionSet::~VersionSet() {
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for (Version* v = oldest_; v != NULL; ) {
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Version* next = v->next_;
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assert(v->refs_ == 0);
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delete v;
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v = next;
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}
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delete descriptor_log_;
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delete descriptor_file_;
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}
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Status VersionSet::LogAndApply(VersionEdit* edit, MemTable* cleanup_mem) {
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if (edit->has_log_number_) {
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assert(edit->log_number_ >= log_number_);
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assert(edit->log_number_ < next_file_number_);
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} else {
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edit->SetLogNumber(log_number_);
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}
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if (!edit->has_prev_log_number_) {
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edit->SetPrevLogNumber(prev_log_number_);
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}
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edit->SetNextFile(next_file_number_);
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edit->SetLastSequence(last_sequence_);
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Version* v = new Version(this);
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{
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Builder builder(this, current_);
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builder.Apply(edit);
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builder.SaveTo(v);
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}
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std::string new_manifest_file;
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Status s = Finalize(v);
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// Initialize new descriptor log file if necessary by creating
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// a temporary file that contains a snapshot of the current version.
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if (s.ok()) {
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if (descriptor_log_ == NULL) {
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assert(descriptor_file_ == NULL);
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new_manifest_file = DescriptorFileName(dbname_, manifest_file_number_);
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edit->SetNextFile(next_file_number_);
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s = env_->NewWritableFile(new_manifest_file, &descriptor_file_);
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if (s.ok()) {
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descriptor_log_ = new log::Writer(descriptor_file_);
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s = WriteSnapshot(descriptor_log_);
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}
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}
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}
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// Write new record to MANIFEST log
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if (s.ok()) {
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std::string record;
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edit->EncodeTo(&record);
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s = descriptor_log_->AddRecord(record);
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if (s.ok()) {
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s = descriptor_file_->Sync();
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}
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}
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// If we just created a new descriptor file, install it by writing a
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// new CURRENT file that points to it.
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if (s.ok() && !new_manifest_file.empty()) {
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s = SetCurrentFile(env_, dbname_, manifest_file_number_);
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}
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// Install the new version
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if (s.ok()) {
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assert(current_->next_ == NULL);
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assert(current_->cleanup_mem_ == NULL);
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current_->cleanup_mem_ = cleanup_mem;
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v->next_ = NULL;
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current_->next_ = v;
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current_ = v;
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log_number_ = edit->log_number_;
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prev_log_number_ = edit->prev_log_number_;
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} else {
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delete v;
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if (!new_manifest_file.empty()) {
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delete descriptor_log_;
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delete descriptor_file_;
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descriptor_log_ = NULL;
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descriptor_file_ = NULL;
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env_->DeleteFile(new_manifest_file);
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}
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}
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return s;
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}
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Status VersionSet::Recover() {
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struct LogReporter : public log::Reader::Reporter {
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Status* status;
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virtual void Corruption(size_t bytes, const Status& s) {
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if (this->status->ok()) *this->status = s;
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}
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};
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// Read "CURRENT" file, which contains a pointer to the current manifest file
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std::string current;
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Status s = ReadFileToString(env_, CurrentFileName(dbname_), ¤t);
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if (!s.ok()) {
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return s;
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}
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if (current.empty() || current[current.size()-1] != '\n') {
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return Status::Corruption("CURRENT file does not end with newline");
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}
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current.resize(current.size() - 1);
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std::string dscname = dbname_ + "/" + current;
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SequentialFile* file;
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s = env_->NewSequentialFile(dscname, &file);
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if (!s.ok()) {
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return s;
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}
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bool have_log_number = false;
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bool have_prev_log_number = false;
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bool have_next_file = false;
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bool have_last_sequence = false;
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uint64_t next_file = 0;
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uint64_t last_sequence = 0;
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uint64_t log_number = 0;
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uint64_t prev_log_number = 0;
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Builder builder(this, current_);
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{
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LogReporter reporter;
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reporter.status = &s;
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log::Reader reader(file, &reporter, true/*checksum*/);
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Slice record;
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std::string scratch;
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while (reader.ReadRecord(&record, &scratch) && s.ok()) {
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VersionEdit edit;
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s = edit.DecodeFrom(record);
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if (s.ok()) {
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if (edit.has_comparator_ &&
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edit.comparator_ != icmp_.user_comparator()->Name()) {
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s = Status::InvalidArgument(
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edit.comparator_ + "does not match existing comparator ",
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icmp_.user_comparator()->Name());
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}
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}
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if (s.ok()) {
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builder.Apply(&edit);
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}
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if (edit.has_log_number_) {
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log_number = edit.log_number_;
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have_log_number = true;
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}
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if (edit.has_prev_log_number_) {
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prev_log_number = edit.prev_log_number_;
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have_prev_log_number = true;
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}
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if (edit.has_next_file_number_) {
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next_file = edit.next_file_number_;
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have_next_file = true;
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}
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if (edit.has_last_sequence_) {
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last_sequence = edit.last_sequence_;
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have_last_sequence = true;
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}
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}
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}
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delete file;
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file = NULL;
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if (s.ok()) {
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if (!have_next_file) {
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s = Status::Corruption("no meta-nextfile entry in descriptor");
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} else if (!have_log_number) {
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s = Status::Corruption("no meta-lognumber entry in descriptor");
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} else if (!have_last_sequence) {
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s = Status::Corruption("no last-sequence-number entry in descriptor");
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}
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if (!have_prev_log_number) {
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prev_log_number = 0;
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}
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}
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if (s.ok()) {
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Version* v = new Version(this);
|
|
builder.SaveTo(v);
|
|
s = Finalize(v);
|
|
if (!s.ok()) {
|
|
delete v;
|
|
} else {
|
|
// Install recovered version
|
|
v->next_ = NULL;
|
|
current_->next_ = v;
|
|
current_ = v;
|
|
manifest_file_number_ = next_file;
|
|
next_file_number_ = next_file + 1;
|
|
last_sequence_ = last_sequence;
|
|
log_number_ = log_number;
|
|
prev_log_number_ = prev_log_number;
|
|
}
|
|
}
|
|
|
|
return s;
|
|
}
|
|
|
|
static int64_t TotalFileSize(const std::vector<FileMetaData*>& files) {
|
|
int64_t sum = 0;
|
|
for (int i = 0; i < files.size(); i++) {
|
|
sum += files[i]->file_size;
|
|
}
|
|
return sum;
|
|
}
|
|
|
|
Status VersionSet::Finalize(Version* v) {
|
|
// Precomputed best level for next compaction
|
|
int best_level = -1;
|
|
double best_score = -1;
|
|
|
|
Status s;
|
|
for (int level = 0; s.ok() && level < config::kNumLevels-1; level++) {
|
|
s = SortLevel(v, level);
|
|
|
|
double score;
|
|
if (level == 0) {
|
|
// We treat level-0 specially by bounding the number of files
|
|
// instead of number of bytes for two reasons:
|
|
//
|
|
// (1) With larger write-buffer sizes, it is nice not to do too
|
|
// many level-0 compactions.
|
|
//
|
|
// (2) The files in level-0 are merged on every read and
|
|
// therefore we wish to avoid too many files when the individual
|
|
// file size is small (perhaps because of a small write-buffer
|
|
// setting, or very high compression ratios, or lots of
|
|
// overwrites/deletions).
|
|
score = v->files_[level].size() / 4.0;
|
|
} else {
|
|
// Compute the ratio of current size to size limit.
|
|
const uint64_t level_bytes = TotalFileSize(v->files_[level]);
|
|
score = static_cast<double>(level_bytes) / MaxBytesForLevel(level);
|
|
}
|
|
|
|
if (score > best_score) {
|
|
best_level = level;
|
|
best_score = score;
|
|
}
|
|
}
|
|
|
|
v->compaction_level_ = best_level;
|
|
v->compaction_score_ = best_score;
|
|
return s;
|
|
}
|
|
|
|
Status VersionSet::WriteSnapshot(log::Writer* log) {
|
|
// TODO: Break up into multiple records to reduce memory usage on recovery?
|
|
|
|
// Save metadata
|
|
VersionEdit edit;
|
|
edit.SetComparatorName(icmp_.user_comparator()->Name());
|
|
|
|
// Save compaction pointers
|
|
for (int level = 0; level < config::kNumLevels; level++) {
|
|
if (!compact_pointer_[level].empty()) {
|
|
InternalKey key;
|
|
key.DecodeFrom(compact_pointer_[level]);
|
|
edit.SetCompactPointer(level, key);
|
|
}
|
|
}
|
|
|
|
// Save files
|
|
for (int level = 0; level < config::kNumLevels; level++) {
|
|
const std::vector<FileMetaData*>& files = current_->files_[level];
|
|
for (int i = 0; i < files.size(); i++) {
|
|
const FileMetaData* f = files[i];
|
|
edit.AddFile(level, f->number, f->file_size, f->smallest, f->largest);
|
|
}
|
|
}
|
|
|
|
// Save large value refs
|
|
for (LargeValueMap::const_iterator it = large_value_refs_.begin();
|
|
it != large_value_refs_.end();
|
|
++it) {
|
|
const LargeValueRef& ref = it->first;
|
|
const LargeReferencesSet& pointers = it->second;
|
|
for (LargeReferencesSet::const_iterator j = pointers.begin();
|
|
j != pointers.end();
|
|
++j) {
|
|
edit.AddLargeValueRef(ref, j->first, j->second);
|
|
}
|
|
}
|
|
|
|
std::string record;
|
|
edit.EncodeTo(&record);
|
|
return log->AddRecord(record);
|
|
}
|
|
|
|
// Helper to sort by tables_[file_number].smallest
|
|
struct VersionSet::BySmallestKey {
|
|
const InternalKeyComparator* internal_comparator;
|
|
|
|
bool operator()(FileMetaData* f1, FileMetaData* f2) const {
|
|
return internal_comparator->Compare(f1->smallest, f2->smallest) < 0;
|
|
}
|
|
};
|
|
|
|
Status VersionSet::SortLevel(Version* v, uint64_t level) {
|
|
Status result;
|
|
BySmallestKey cmp;
|
|
cmp.internal_comparator = &icmp_;
|
|
std::sort(v->files_[level].begin(), v->files_[level].end(), cmp);
|
|
|
|
if (result.ok() && level > 0) {
|
|
// There should be no overlap
|
|
for (int i = 1; i < v->files_[level].size(); i++) {
|
|
const InternalKey& prev_end = v->files_[level][i-1]->largest;
|
|
const InternalKey& this_begin = v->files_[level][i]->smallest;
|
|
if (icmp_.Compare(prev_end, this_begin) >= 0) {
|
|
result = Status::Corruption(
|
|
"overlapping ranges in same level",
|
|
(EscapeString(prev_end.Encode()) + " vs. " +
|
|
EscapeString(this_begin.Encode())));
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
return result;
|
|
}
|
|
|
|
int VersionSet::NumLevelFiles(int level) const {
|
|
assert(level >= 0);
|
|
assert(level < config::kNumLevels);
|
|
return current_->files_[level].size();
|
|
}
|
|
|
|
uint64_t VersionSet::ApproximateOffsetOf(Version* v, const InternalKey& ikey) {
|
|
uint64_t result = 0;
|
|
for (int level = 0; level < config::kNumLevels; level++) {
|
|
const std::vector<FileMetaData*>& files = v->files_[level];
|
|
for (int i = 0; i < files.size(); i++) {
|
|
if (icmp_.Compare(files[i]->largest, ikey) <= 0) {
|
|
// Entire file is before "ikey", so just add the file size
|
|
result += files[i]->file_size;
|
|
} else if (icmp_.Compare(files[i]->smallest, ikey) > 0) {
|
|
// Entire file is after "ikey", so ignore
|
|
if (level > 0) {
|
|
// Files other than level 0 are sorted by meta->smallest, so
|
|
// no further files in this level will contain data for
|
|
// "ikey".
|
|
break;
|
|
}
|
|
} else {
|
|
// "ikey" falls in the range for this table. Add the
|
|
// approximate offset of "ikey" within the table.
|
|
Table* tableptr;
|
|
Iterator* iter = table_cache_->NewIterator(
|
|
ReadOptions(), files[i]->number, files[i]->file_size, &tableptr);
|
|
if (tableptr != NULL) {
|
|
result += tableptr->ApproximateOffsetOf(ikey.Encode());
|
|
}
|
|
delete iter;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Add in large value files which are references from internal keys
|
|
// stored in the table files
|
|
//
|
|
// TODO(opt): this is O(# large values in db). If this becomes too slow,
|
|
// we could store an auxiliary data structure indexed by internal key
|
|
for (LargeValueMap::const_iterator it = large_value_refs_.begin();
|
|
it != large_value_refs_.end();
|
|
++it) {
|
|
const LargeValueRef& lref = it->first;
|
|
for (LargeReferencesSet::const_iterator it2 = it->second.begin();
|
|
it2 != it->second.end();
|
|
++it2) {
|
|
if (icmp_.Compare(it2->second, ikey.Encode()) <= 0) {
|
|
// Internal key for large value is before our key of interest
|
|
result += lref.ValueSize();
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
return result;
|
|
}
|
|
|
|
bool VersionSet::RegisterLargeValueRef(const LargeValueRef& large_ref,
|
|
uint64_t fnum,
|
|
const InternalKey& internal_key) {
|
|
LargeReferencesSet* refs = &large_value_refs_[large_ref];
|
|
bool is_first = refs->empty();
|
|
refs->insert(make_pair(fnum, internal_key.Encode().ToString()));
|
|
return is_first;
|
|
}
|
|
|
|
void VersionSet::CleanupLargeValueRefs(const std::set<uint64_t>& live_tables) {
|
|
for (LargeValueMap::iterator it = large_value_refs_.begin();
|
|
it != large_value_refs_.end();
|
|
) {
|
|
LargeReferencesSet* refs = &it->second;
|
|
for (LargeReferencesSet::iterator ref_it = refs->begin();
|
|
ref_it != refs->end();
|
|
) {
|
|
if (ref_it->first != log_number_ && // Not in log file
|
|
ref_it->first != prev_log_number_ && // Not in prev log
|
|
live_tables.count(ref_it->first) == 0) { // Not in a live table
|
|
// No longer live: erase
|
|
LargeReferencesSet::iterator to_erase = ref_it;
|
|
++ref_it;
|
|
refs->erase(to_erase);
|
|
} else {
|
|
// Still live: leave this reference alone
|
|
++ref_it;
|
|
}
|
|
}
|
|
if (refs->empty()) {
|
|
// No longer any live references to this large value: remove from
|
|
// large_value_refs
|
|
Log(env_, options_->info_log, "large value is dead: '%s'",
|
|
LargeValueRefToFilenameString(it->first).c_str());
|
|
LargeValueMap::iterator to_erase = it;
|
|
++it;
|
|
large_value_refs_.erase(to_erase);
|
|
} else {
|
|
++it;
|
|
}
|
|
}
|
|
}
|
|
|
|
bool VersionSet::LargeValueIsLive(const LargeValueRef& large_ref) {
|
|
LargeValueMap::iterator it = large_value_refs_.find(large_ref);
|
|
if (it == large_value_refs_.end()) {
|
|
return false;
|
|
} else {
|
|
assert(!it->second.empty());
|
|
return true;
|
|
}
|
|
}
|
|
|
|
void VersionSet::MaybeDeleteOldVersions() {
|
|
// Note: it is important to delete versions in order since a newer
|
|
// version with zero refs may be holding a pointer to a memtable
|
|
// that is used by somebody who has a ref on an older version.
|
|
while (oldest_ != current_ && oldest_->refs_ == 0) {
|
|
Version* next = oldest_->next_;
|
|
delete oldest_;
|
|
oldest_ = next;
|
|
}
|
|
}
|
|
|
|
void VersionSet::AddLiveFiles(std::set<uint64_t>* live) {
|
|
for (Version* v = oldest_; v != NULL; v = v->next_) {
|
|
for (int level = 0; level < config::kNumLevels; level++) {
|
|
const std::vector<FileMetaData*>& files = v->files_[level];
|
|
for (int i = 0; i < files.size(); i++) {
|
|
live->insert(files[i]->number);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
int64_t VersionSet::NumLevelBytes(int level) const {
|
|
assert(level >= 0);
|
|
assert(level < config::kNumLevels);
|
|
return TotalFileSize(current_->files_[level]);
|
|
}
|
|
|
|
int64_t VersionSet::MaxNextLevelOverlappingBytes() {
|
|
int64_t result = 0;
|
|
std::vector<FileMetaData*> overlaps;
|
|
for (int level = 0; level < config::kNumLevels - 1; level++) {
|
|
for (int i = 0; i < current_->files_[level].size(); i++) {
|
|
const FileMetaData* f = current_->files_[level][i];
|
|
GetOverlappingInputs(level+1, f->smallest, f->largest, &overlaps);
|
|
const int64_t sum = TotalFileSize(overlaps);
|
|
if (sum > result) {
|
|
result = sum;
|
|
}
|
|
}
|
|
}
|
|
return result;
|
|
}
|
|
|
|
// Store in "*inputs" all files in "level" that overlap [begin,end]
|
|
void VersionSet::GetOverlappingInputs(
|
|
int level,
|
|
const InternalKey& begin,
|
|
const InternalKey& end,
|
|
std::vector<FileMetaData*>* inputs) {
|
|
inputs->clear();
|
|
Slice user_begin = begin.user_key();
|
|
Slice user_end = end.user_key();
|
|
const Comparator* user_cmp = icmp_.user_comparator();
|
|
for (int i = 0; i < current_->files_[level].size(); i++) {
|
|
FileMetaData* f = current_->files_[level][i];
|
|
if (user_cmp->Compare(f->largest.user_key(), user_begin) < 0 ||
|
|
user_cmp->Compare(f->smallest.user_key(), user_end) > 0) {
|
|
// Either completely before or after range; skip it
|
|
} else {
|
|
inputs->push_back(f);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Stores the minimal range that covers all entries in inputs in
|
|
// *smallest, *largest.
|
|
// REQUIRES: inputs is not empty
|
|
void VersionSet::GetRange(const std::vector<FileMetaData*>& inputs,
|
|
InternalKey* smallest,
|
|
InternalKey* largest) {
|
|
assert(!inputs.empty());
|
|
smallest->Clear();
|
|
largest->Clear();
|
|
for (int i = 0; i < inputs.size(); i++) {
|
|
FileMetaData* f = inputs[i];
|
|
if (i == 0) {
|
|
*smallest = f->smallest;
|
|
*largest = f->largest;
|
|
} else {
|
|
if (icmp_.Compare(f->smallest, *smallest) < 0) {
|
|
*smallest = f->smallest;
|
|
}
|
|
if (icmp_.Compare(f->largest, *largest) > 0) {
|
|
*largest = f->largest;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Stores the minimal range that covers all entries in inputs1 and inputs2
|
|
// in *smallest, *largest.
|
|
// REQUIRES: inputs is not empty
|
|
void VersionSet::GetRange2(const std::vector<FileMetaData*>& inputs1,
|
|
const std::vector<FileMetaData*>& inputs2,
|
|
InternalKey* smallest,
|
|
InternalKey* largest) {
|
|
std::vector<FileMetaData*> all = inputs1;
|
|
all.insert(all.end(), inputs2.begin(), inputs2.end());
|
|
GetRange(all, smallest, largest);
|
|
}
|
|
|
|
Iterator* VersionSet::MakeInputIterator(Compaction* c) {
|
|
ReadOptions options;
|
|
options.verify_checksums = options_->paranoid_checks;
|
|
options.fill_cache = false;
|
|
|
|
// Level-0 files have to be merged together. For other levels,
|
|
// we will make a concatenating iterator per level.
|
|
// TODO(opt): use concatenating iterator for level-0 if there is no overlap
|
|
const int space = (c->level() == 0 ? c->inputs_[0].size() + 1 : 2);
|
|
Iterator** list = new Iterator*[space];
|
|
int num = 0;
|
|
for (int which = 0; which < 2; which++) {
|
|
if (!c->inputs_[which].empty()) {
|
|
if (c->level() + which == 0) {
|
|
const std::vector<FileMetaData*>& files = c->inputs_[which];
|
|
for (int i = 0; i < files.size(); i++) {
|
|
list[num++] = table_cache_->NewIterator(
|
|
options, files[i]->number, files[i]->file_size);
|
|
}
|
|
} else {
|
|
// Create concatenating iterator for the files from this level
|
|
list[num++] = NewTwoLevelIterator(
|
|
new Version::LevelFileNumIterator(
|
|
c->input_version_, &c->inputs_[which]),
|
|
&GetFileIterator, table_cache_, options);
|
|
}
|
|
}
|
|
}
|
|
assert(num <= space);
|
|
Iterator* result = NewMergingIterator(&icmp_, list, num);
|
|
delete[] list;
|
|
return result;
|
|
}
|
|
|
|
Compaction* VersionSet::PickCompaction() {
|
|
if (!NeedsCompaction()) {
|
|
return NULL;
|
|
}
|
|
const int level = current_->compaction_level_;
|
|
assert(level >= 0);
|
|
assert(level+1 < config::kNumLevels);
|
|
|
|
Compaction* c = new Compaction(level);
|
|
c->input_version_ = current_;
|
|
c->input_version_->Ref();
|
|
|
|
// Pick the first file that comes after compact_pointer_[level]
|
|
for (int i = 0; i < current_->files_[level].size(); i++) {
|
|
FileMetaData* f = current_->files_[level][i];
|
|
if (compact_pointer_[level].empty() ||
|
|
icmp_.Compare(f->largest.Encode(), compact_pointer_[level]) > 0) {
|
|
c->inputs_[0].push_back(f);
|
|
break;
|
|
}
|
|
}
|
|
if (c->inputs_[0].empty()) {
|
|
// Wrap-around to the beginning of the key space
|
|
c->inputs_[0].push_back(current_->files_[level][0]);
|
|
}
|
|
|
|
// Files in level 0 may overlap each other, so pick up all overlapping ones
|
|
if (level == 0) {
|
|
InternalKey smallest, largest;
|
|
GetRange(c->inputs_[0], &smallest, &largest);
|
|
// Note that the next call will discard the file we placed in
|
|
// c->inputs_[0] earlier and replace it with an overlapping set
|
|
// which will include the picked file.
|
|
GetOverlappingInputs(0, smallest, largest, &c->inputs_[0]);
|
|
assert(!c->inputs_[0].empty());
|
|
}
|
|
|
|
SetupOtherInputs(c);
|
|
|
|
return c;
|
|
}
|
|
|
|
void VersionSet::SetupOtherInputs(Compaction* c) {
|
|
const int level = c->level();
|
|
InternalKey smallest, largest;
|
|
GetRange(c->inputs_[0], &smallest, &largest);
|
|
|
|
GetOverlappingInputs(level+1, smallest, largest, &c->inputs_[1]);
|
|
|
|
// Get entire range covered by compaction
|
|
InternalKey all_start, all_limit;
|
|
GetRange2(c->inputs_[0], c->inputs_[1], &all_start, &all_limit);
|
|
|
|
// See if we can grow the number of inputs in "level" without
|
|
// changing the number of "level+1" files we pick up.
|
|
if (!c->inputs_[1].empty()) {
|
|
std::vector<FileMetaData*> expanded0;
|
|
GetOverlappingInputs(level, all_start, all_limit, &expanded0);
|
|
if (expanded0.size() > c->inputs_[0].size()) {
|
|
InternalKey new_start, new_limit;
|
|
GetRange(expanded0, &new_start, &new_limit);
|
|
std::vector<FileMetaData*> expanded1;
|
|
GetOverlappingInputs(level+1, new_start, new_limit, &expanded1);
|
|
if (expanded1.size() == c->inputs_[1].size()) {
|
|
Log(env_, options_->info_log,
|
|
"Expanding@%d %d+%d to %d+%d\n",
|
|
level,
|
|
int(c->inputs_[0].size()),
|
|
int(c->inputs_[1].size()),
|
|
int(expanded0.size()),
|
|
int(expanded1.size()));
|
|
smallest = new_start;
|
|
largest = new_limit;
|
|
c->inputs_[0] = expanded0;
|
|
c->inputs_[1] = expanded1;
|
|
GetRange2(c->inputs_[0], c->inputs_[1], &all_start, &all_limit);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Compute the set of grandparent files that overlap this compaction
|
|
// (parent == level+1; grandparent == level+2)
|
|
if (level + 2 < config::kNumLevels) {
|
|
GetOverlappingInputs(level + 2, all_start, all_limit, &c->grandparents_);
|
|
}
|
|
|
|
if (false) {
|
|
Log(env_, options_->info_log, "Compacting %d '%s' .. '%s'",
|
|
level,
|
|
EscapeString(smallest.Encode()).c_str(),
|
|
EscapeString(largest.Encode()).c_str());
|
|
}
|
|
|
|
// Update the place where we will do the next compaction for this level.
|
|
// We update this immediately instead of waiting for the VersionEdit
|
|
// to be applied so that if the compaction fails, we will try a different
|
|
// key range next time.
|
|
compact_pointer_[level] = largest.Encode().ToString();
|
|
c->edit_.SetCompactPointer(level, largest);
|
|
}
|
|
|
|
Compaction* VersionSet::CompactRange(
|
|
int level,
|
|
const InternalKey& begin,
|
|
const InternalKey& end) {
|
|
std::vector<FileMetaData*> inputs;
|
|
GetOverlappingInputs(level, begin, end, &inputs);
|
|
if (inputs.empty()) {
|
|
return NULL;
|
|
}
|
|
|
|
Compaction* c = new Compaction(level);
|
|
c->input_version_ = current_;
|
|
c->input_version_->Ref();
|
|
c->inputs_[0] = inputs;
|
|
SetupOtherInputs(c);
|
|
return c;
|
|
}
|
|
|
|
Compaction::Compaction(int level)
|
|
: level_(level),
|
|
max_output_file_size_(MaxFileSizeForLevel(level)),
|
|
input_version_(NULL),
|
|
grandparent_index_(0),
|
|
seen_key_(false),
|
|
overlapped_bytes_(0) {
|
|
for (int i = 0; i < config::kNumLevels; i++) {
|
|
level_ptrs_[i] = 0;
|
|
}
|
|
}
|
|
|
|
Compaction::~Compaction() {
|
|
if (input_version_ != NULL) {
|
|
input_version_->Unref();
|
|
}
|
|
}
|
|
|
|
bool Compaction::IsTrivialMove() const {
|
|
// Avoid a move if there is lots of overlapping grandparent data.
|
|
// Otherwise, the move could create a parent file that will require
|
|
// a very expensive merge later on.
|
|
return (num_input_files(0) == 1 &&
|
|
num_input_files(1) == 0 &&
|
|
TotalFileSize(grandparents_) <= kMaxGrandParentOverlapBytes);
|
|
}
|
|
|
|
void Compaction::AddInputDeletions(VersionEdit* edit) {
|
|
for (int which = 0; which < 2; which++) {
|
|
for (int i = 0; i < inputs_[which].size(); i++) {
|
|
edit->DeleteFile(level_ + which, inputs_[which][i]->number);
|
|
}
|
|
}
|
|
}
|
|
|
|
bool Compaction::IsBaseLevelForKey(const Slice& user_key) {
|
|
// Maybe use binary search to find right entry instead of linear search?
|
|
const Comparator* user_cmp = input_version_->vset_->icmp_.user_comparator();
|
|
for (int lvl = level_ + 2; lvl < config::kNumLevels; lvl++) {
|
|
const std::vector<FileMetaData*>& files = input_version_->files_[lvl];
|
|
for (; level_ptrs_[lvl] < files.size(); ) {
|
|
FileMetaData* f = files[level_ptrs_[lvl]];
|
|
if (user_cmp->Compare(user_key, f->largest.user_key()) <= 0) {
|
|
// We've advanced far enough
|
|
if (user_cmp->Compare(user_key, f->smallest.user_key()) >= 0) {
|
|
// Key falls in this file's range, so definitely not base level
|
|
return false;
|
|
}
|
|
break;
|
|
}
|
|
level_ptrs_[lvl]++;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
bool Compaction::ShouldStopBefore(const InternalKey& key) {
|
|
// Scan to find earliest grandparent file that contains key.
|
|
const InternalKeyComparator* icmp = &input_version_->vset_->icmp_;
|
|
while (grandparent_index_ < grandparents_.size() &&
|
|
icmp->Compare(key, grandparents_[grandparent_index_]->largest) > 0) {
|
|
if (seen_key_) {
|
|
overlapped_bytes_ += grandparents_[grandparent_index_]->file_size;
|
|
}
|
|
grandparent_index_++;
|
|
}
|
|
seen_key_ = true;
|
|
|
|
if (overlapped_bytes_ > kMaxGrandParentOverlapBytes) {
|
|
// Too much overlap for current output; start new output
|
|
overlapped_bytes_ = 0;
|
|
return true;
|
|
} else {
|
|
return false;
|
|
}
|
|
}
|
|
|
|
void Compaction::ReleaseInputs() {
|
|
if (input_version_ != NULL) {
|
|
input_version_->Unref();
|
|
input_version_ = NULL;
|
|
}
|
|
}
|
|
|
|
}
|